Izz Municipal Landfill

Solid waste management is one of the top priorities of the Oman government, leading to the establishment of Be’ah by royal decree to manage and plan the solid waste strategy. As part of this strategy, aging dumpsites were closed and replaced with new, large, regional, engineered containment landfills. The Izz Landfill facility services the Al Dakhiliya Governate, located approximately 140km southwest of Muscat with Nizwa as its capital. The project required the design and construction of a 20-year, 4.8 million m³ extension to the existing municipal solid waste (MSW) landfill to enhance the region’s waste management capabilities.

From 2015 to 2019, Ayesa worked on behalf of Al Ahlia Environmental Services to provide a masterplan design for the 20-year landfill extension and the detailed design for the first two phases of the project. Al Ahlia was contracted to construct these two phases, which provided an initial 2 million m³ of sanitary landfill capacity with associated infrastructure, including two new leachate evaporation ponds (4000 m²). Our role included supervising the construction, ensuring quality assurance and verification of the works, and preparing operational, monitoring, and closure plans.

Before construction, our team conducted initial desk studies and appraisals to identify environmental risks and optimize the landfill design. These studies included borehole investigations, background groundwater monitoring, geotechnical studies, trial excavation/rippability investigations, geological, hydrogeological, and hydrological assessments, and a flood risk assessment. Following the approval of the masterplan design by Be’ah, we provided the detailed design of Phases 2 & 3 of the landfill, which included surface water management plans, earthworks, and containment engineering design (composite HDPE/GCL lining system).

We also designed and specified the large-scale earthworks, geosynthetic and aggregate leachate drainage systems, and the geosynthetic cap, all to EU/USEPA standards. Our scope included the design and specification of the leachate collection, pumping, and treatment systems; the landfill gas management system, environmental monitoring systems, and the surface water management plan. Additionally, we undertook the design of the necessary infrastructure for both the construction and operational phases, including 2-way asphalt roads, roundabouts, access ramps, wheel wash, fencing, and storage areas.

Ayesa’s engineering team ensured that all work adhered to the highest standards, from the detailed design phase through to construction support. Our role involved preparing the technical specifications and providing ongoing construction support to ensure that all works were completed to the highest quality. The 20-year master plan included best practices for environmental monitoring and operations, as well as procedures and planning for eventual closure. Throughout the project, our progress was regularly presented to stakeholders, including Be’ah, to ensure alignment and collaboration. The site was handed over progressively to the landfill operator as each phase was completed, ensuring uninterrupted service to the local community.